The video shows an authorization code (a different one) being returned to what’s likely the application configured callback URL. Given that after you authenticate there’s a session established in the Auth0 tenant/domain which may be reused for subsequent login requests the most likely reason for this situation is the client application logic having an issue that prevents it from completing the login flow and because of that redirecting again to login.
The loop is triggered because the application continuously redirects to login while the Auth0 tenant domain continuously responds with a success response as the user already authenticated and a session exists.
Given this is triggered by something the application logic does in order to troubleshoot this you will need to review the application logic itself. A good starting point would be to capture an HTTP trace of a working login and also of a failed one (the loop thing); once you have that you would do a comparison check to see if there’s anything different at the network level (for example, are there cookies present in the requests associated with the client application in the working one, but not in the failed one).